A dinâmica dos manguezais no Nordeste do Brasil: uma abordagem a partir de dados de sensores remotos e SIG.

Abstract

This study assesses the dynamics of mangroves in the northeastern Brazil in the last four decades from the classification of remote sensing images based on geographic objects (GEOBIA). This methodology combines spectral, temporal and spatial information of multi-temporal images to create consistent objects (mangrove areas) for a statistical analysis from classified images. The objective of this study was to evaluate the changes in mangrove forest cover in all states of the northeastern Brazil between 1975 and 2008, with regard to the increase or decrease mangrove areas in response to natural (erosion and accretion) and anthropogenic (Aquaculture / salinicultura) variations. In this study were processed and analyzed remote sensing images (RADAMBRASIL, ALOS PALSAR, TM Landsat and SRTM) from GEOBIA approach. During the studied period, there was a reduction of ~ 1,545 km2 mangrove forest area in 1975 to ~ 1480 km2 in 2008. This represents a net loss of ~ 65 km2, which is equivalent to a decrease of 13% in the mangrove forest area. Of the nine states studied, only Ceará and Pernambuco showed a gain in coverage of mangroves, while all others were reduced. Among the total mangrove forest area lost during the study period (~ 953 km2), the aquaculture/saliniculture ponds represent ~ 10%. Importantly, in the states of Rio Grande do Norte and Ceará the conversion of mangrove areas for aquaculture/saliniculture ponds already represent ~ 41% and 32% of the total area of mangrove lost, respectively. Therefore, it concludes that the methodology used to assess the dynamics of mangroves in northeastern Brazil from different sources of remote sensing data was extremely effective. New strategies for recovery and sustainable use of mangrove areas should be established in order to conserve this ecosystem for future generations.